Moparts

Transbrake in a 11.30 car w/ a stock 904 & 8/34?

Posted By: dustyhof

Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/10/09 11:40 PM

Thinking about a transbrake for the Dart to help with my lights. Right now the car runs 11.30's @ 3000#, with a basically stock 904 and a 8 3/4 with pro gears and a spool. If I keep the launch RPM's down, will it live or will I start breaking stuff? A Dana 60 and a built trans is in the plans, but is a little while down the road. Should I wait, or will it be OK?
Posted By: Dan Brewer

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/10/09 11:46 PM

Sell the 8 3/4 and 904 b4 they break. Spend the $$ to build the dana 1st.
Posted By: WILD BILL

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/10/09 11:47 PM

What kind of front drum do you have?
Posted By: dustyhof

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/10/09 11:53 PM

Quote:

What kind of front drum do you have?



Pretty sure it's stock. I think the only thing done to this tranny is a low 1st gear set, and a Cheetah manual VB. Dad built the tranny, and he's not around to ask any more.
Posted By: MR_P_BODY

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/10/09 11:56 PM

Quote:

Thinking about a transbrake for the Dart to help with my lights. Right now the car runs 11.30's @ 3000#, with a basically stock 904 and a 8 3/4 with pro gears and a spool. If I keep the launch RPM's down, will it live or will I start breaking stuff? A Dana 60 and a built trans is in the plans, but is a little while down the road. Should I wait, or will it be OK?





I've been using a trans brake since I build my car,
the only thing I would suggest would be caps in the
rearend and a back brace... I use the alum center
8 3/4 and a brace... with a 1.19 60'.... your right
at the weight where I would think about changing the
diff(to me its the weight that kills a 8 3/4)... I
use a 727 but I know ALOT of guys using a 904 with
a brake
Posted By: dustyhof

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 12:05 AM

I'm planning on changing to a better rear and tranny. Problem is it won't happen until at least after next season. (this stuff all costs money ) Will I break the stuff I have now, or should I just footbrake another season? I really don't want to do a bunch of work on my 8 3/4, when it's coming out anyway. I also don't want to break it before I'm ready to put the good rear in.
Posted By: MR_P_BODY

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 12:11 AM

Quote:

I'm planning on changing to a better rear and tranny. Problem is it won't happen until at least after next season. (this stuff all costs money ) Will I break the stuff I have now, or should I just footbrake another season? I really don't want to do a bunch of work on my 8 3/4, when it's coming out anyway. I also don't want to break it before I'm ready to put the good rear in.




Continue as you are now.... that way you are pretty
much assured you'd be ok.... JMO
Posted By: dustyhof

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 12:13 AM

Will do. Better safe than sorry I guess. Thanks again. You have been a huge help with all my goofy racing ides! Much appreciated!
Posted By: WILD BILL

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 12:26 AM

Just look at what happened to me when I put in a T brake with a stock front drum.

FWIW I'm now using Mancini's nodular 489 case in my 8 3/4. I don't think it was the brake that killed the OE one though. I think it was a U joint that started it all.
Posted By: Tommy D

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 12:31 AM

I've been watching this post a little, and I love your Dart. My question is this. If you are having trouble with your lights, work on fixing your reaction time in other ways. Put a shorter tire on the front. That will help with the rollout. Increase the RPM a little. If you don't have one...BUY A PRACTICE TREE. It's the best investment I ever made for my racing ventures.

If you are bracket racing, the tire spin you will receive with the smallish slicks on your Dart would outweigh the lazy lights in my opinion. When you consider the issues with broken parts or spending big bucks for expensive drive train components...why bother. Keep your money in the bank for unseen breakage down the road. Work on fixing the problem, and you will be a happier racer. Good luck.
Posted By: dustyhof

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 12:31 AM

Quote:

Just look at what happened to me when I put in a T brake with a stock front drum.

FWIW I'm now using Mancini's nodular 489 case in my 8 3/4. I don't think it was the brake that killed the OE one though. I think it was a U joint that started it all.




OK. You guys talked me out of it. Not going to do it until I get a better rear and trans. I'm tossing around the idea of a glide anyway. No sense in buying 2 transbrakes.
Posted By: dustyhof

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 12:37 AM

Quote:

I've been watching this post a little, and I love your Dart. My question is this. If you are having trouble with your lights, work on fixing your reaction time in other ways. Put a shorter tire on the front. That will help with the rollout. Increase the RPM a little. If you don't have one...BUY A PRACTICE TREE. It's the best investment I ever made for my racing ventures.

If you are bracket racing, the tire spin you will receive with the smallish slicks on your Dart would outweigh the lazy lights in my opinion. When you consider the issues with broken parts or spending big bucks for expensive drive train components...why bother. Keep your money in the bank for unseen breakage down the road. Work on fixing the problem, and you will be a happier racer. Good luck.



I don't have lazy lights, just inconsistent lights. Just thought a button would make the car a bit more competitive, that's all. Thanks for the compliments on the car, but I'm just trying to be a more competitive racer. I'll spend my money how I like, thank you. Just wanted to know if my parts would hold up, that's all.
Posted By: Quicktree

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 01:05 AM

Quote:

Quote:

I've been watching this post a little, and I love your Dart. My question is this. If you are having trouble with your lights, work on fixing your reaction time in other ways. Put a shorter tire on the front. That will help with the rollout. Increase the RPM a little. If you don't have one...BUY A PRACTICE TREE. It's the best investment I ever made for my racing ventures.

If you are bracket racing, the tire spin you will receive with the smallish slicks on your Dart would outweigh the lazy lights in my opinion. When you consider the issues with broken parts or spending big bucks for expensive drive train components...why bother. Keep your money in the bank for unseen breakage down the road. Work on fixing the problem, and you will be a happier racer. Good luck.



I don't have lazy lights, just inconsistent lights. Just thought a button would make the car a bit more competitive, that's all. Thanks for the compliments on the car, but I'm just trying to be a more competitive racer. I'll spend my money how I like, thank you. Just wanted to know if my parts would hold up, that's all.




get a practice tree and all the seat time you can. make sure your car is capable of running the number. then worry about everything else.
Posted By: 70AARcuda

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 01:56 AM

71 dart with 360/904/ 8 3/4 going on 3rd year racing...

trans ordinally was stock except transbrake...ran whole year on it...replaced engine..

while changing out 360 to faster engine...i rebuild 904 ...upgraded to 5 disc in front clutch...24 spring kit to replace large spring in front drum piston....and using kelvar bands...
deep sump from summit..and tranzact brake.

dart has run a best of 11.00s in las vegas..
Posted By: S/ST 3040

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 02:56 AM

I don't think you need anything fancy in a 904, especially @ 11.30. Mines
going together with almost all stock parts.(both drums, gear sets, shafts)
with an A&A Pro-brake, high-gear spring kit and a deep pan. I will put an
aluminum front drum in it when I free up the cash.

BTW, 904s and 727s valve bodies interchange.
Posted By: 70dusterjohn

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 03:11 AM

If it were me, I'd wait for the new rear...
Posted By: S/ST 3040

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 03:25 AM

But, it's fun while it lasts.

Attached picture 5409851-DSCN1534.JPG
Posted By: Anonymous

Post deleted by Defbob - 08/11/09 03:30 AM

Posted By: J_BODY

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 04:24 AM

Here's what our old 360 (10.9/low 11) did to our stock 8.75 axles. We lost a set of gears a couple years back too.



....I still had a set of stock spline Dutchman axles that I used in my car so we put those in the Duster with pretty good success......Until the W5 mill got ahold of them. Twisted those bad. That was the reason the car didn't hit the track until late June. It now has a Dr Diff D60 in place.
Posted By: J_BODY

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 04:43 AM

.....and if you want a 904/Tranz Act brake equipped 904 with a Dynamic converter built to take the abuse I just happen to know where one is sitting.
Posted By: Anonymous

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 07:39 AM

Transbrake in a 11.30 car for what??..my "street" duster with a good built 904.. race clutches,low first gear,full manual valvebody,foot braking 60's in the low 1.40's and pulled my fat [Edited by Moparts - Family Friendly Site - Keep it clean] to 11.0's with a 3.91 suregrip,Moser axles,billet yokes 8 3/4,properly built the 904 and 8 3/4 can take just about anything you throw at them,now if it were a 4-speed car i'd definately go dana..
Posted By: S/ST 3040

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 12:39 PM

Since I don't have any first-hand experience racing 904s, I can
only make this observation........In racing applications, the 904
seems to outlive the 8 3/4" by quite a margine.
Posted By: POZEST

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 12:44 PM

Just playin a little devils advocate here. Anyone ever heard of a 904 exploding a drum? 727 doesn't count. Just curious.
Posted By: S/ST 3040

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 12:47 PM

Never.........904 drums are substantially smaller in diameter and way less mass.

I weighed both OEM drums, completely empty on my digital scales......

727 high gear drum is 3480.5 grams and 7.496" in diameter

904 high gear drum is 2378 grams and 5.876" in diameter

This example shows the 904 drum is 2.43 lbs. lighter and 1.620" less in diameter.

This picture pretty much tells the story.

Attached picture 5410238-DSCN2391.JPG
Posted By: S/ST 3040

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 02:12 PM

You can see one reason why the 904 uses less power.........and why it won't hold as much power.

Attached picture 5410378-DSCN2393.JPG
Posted By: WILD BILL

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/11/09 02:19 PM

FWIW, my issues with the stock front drum in my 727 were with the snap ring and it not being able to stay in place causing the piston lip seals to tear and the clutches to get burned.
Posted By: J_BODY

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/12/09 01:04 AM

...there is a way around that "weight" issue.



I finally "retired" the lightened stock piece last year in favor of a steel aftermarket drum. That drum had 15 years of service.
Posted By: BIG DRAG

Re: Transbrake in a 11.30 car w/ a stock 904 & 8/34? - 08/12/09 07:49 PM

First things first, the 904 will live just fine as long as you have the steel caged planetaries, it will destroy the aluminum caged one!! You will kill the 8 3/4 it is just a matter of time.

If you want to leave off of a button just put one in, wire it up to the two step and leave with it. You will still have to use your foot but I guarantee that you will learn quickly to lead with your hand and your foot will follow. And even if you are a bit slow coming off of the brake pedal the car WILL drive right through the brakes. I did this quite successfully for years before putting a trans brake in my car and it worked great for me!! It used to be the in thing for stock eliminator until they outlawed it!!
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